The present invention relates to clamps for use with a top entry ball valve, and particularly to clamps used when assembling and dismantling the ball valve.
FIG. 1 shows a top entry ball valve disclosed in U.S. patent application Ser. No. 747,959 filed on June 24, 1985. It has a valve casing, a valve body 2, a seat ring 3 disposed between the valve body and a seat receiving surface 1 at the low-pressure side, and a seat ring assembly 8 disposed between the valve body 2 and a seat receiving surface 4 at the high-pressure side. The seat ring assembly 8 consists of a seat ring 5, a belleville spring 6 and a seat ring holder 7.
In order to assemble and dismantle the above said ball valve, the seat ring 3, valve body 2 and seat ring assembly 8 are brought together and mounted and removed into and out of a valve chest 9 with a bonnet 10 removed. When the belleville spring is in its uncompressed state, the seat ring assembly is too thick to be mounted into the valve chest with the seat ring and the valve body. Also, when the valve body 2, seat ring 3, and seat ring assembly 8 are already in the valve chest 9, they cannot be easily taken out of the valve chest because of the resilience of the belleville spring 6.